In the meantime, soak the mushrooms in a good 3/8 l of lukewarm water. Meanwhile, dice the bacon and fry until crispy. Drain the mushrooms while collecting the stock.
Briefly sweat the mushrooms. Deglaze with mushroom water and broth. Simmer for 5 minutes. Stir in sour cream and bacon cubes, bind with sauce binder if necessary. To taste.